Abu Murra, the freed slave of Umm Hani, narrated on the authority of Abu Darda': My Friend (ﷺ) instructed me in three (acts), and I would never abandon them as long as I live. (And these three things are): Three fasts during every month, the forenoon prayer, and that I should not sleep till I have observed the Witr prayer.
Hadith Referenceصحيح مسلم / كتاب صلاة المسافرين وقصرها / 722
Abu Al-Darda said: My friend (i. e. the Prophet) instructed me to observe three practices which I never leave: he instructed me to fast three days every month, and not to sleep but after observing the with, and to observe supererogatory prayer in the forenoon while traveling and while resident.
Shaykh Umar Farooq Saeedi
1433. Commentary: ➊ According to Shaykh al-Albani rahimahullah, in this narration the words [في الحضر والسفر] "during travel and at home" are not authentic. ➋ These individuals were certainly devoted to the night prayer (tahajjud). However, in accordance with the instruction of the Messenger of Allah sallallahu alayhi wa sallam, they used to perform witr before sleeping. ➌ In these ahadith, there is facilitation and encouragement for those who work and for students of knowledge, that they may perform the night prayer (qiyam al-layl) in the first part of the night.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 1433